Three-dimensional numerical analysis of natural convection in horizontal annuli

Numerical analysis has been performed on unsteady three-dimensional natural convection in a concentric horizontal annulus. The vorticity-vector potential formulation and the alternating-direction-implicit (ADI) method are utilized. The structure of three-dimensional spiral flow pattern is clarified, which were obtained numerically and experimentally in the previous paper in spite of the difference in Prandtl number. And experiments are also conducted with air or glycerol to visualize the flow pattern. Incense smoke and zinc stearate powder are used for the visualization of air flow, and aluminum powder for glycerol. Comparison of the numerical and experimental results shows good agreement. (author)